The rapidly growing ranks of the oldest old in the U.S. are facing a health care system that does not accommodate their emerging health care needs, needs that increasingly fall in the gap between the nation's acute and long-term care systems. Borrowing from a European model to address this gap, in October, 1993 the University of Pennsylvania School of Nursing opened a nurse-managed geriatric day hospital--the Collaborative Assessment and Rehabilitation for Elders (CARE) Program. The purpose of this study is to conduct a scientific evaluation of CARE, an interdisciplinary geriatric day hospital that provides comprehensive assessment and short-term intensive rehabilitation services to enhance function in activities of daily living for frail and chronically ill elders who are at risk for hospitalization or nursing home admission without such care. This evaluation will assess the contribution of the day hospital to improved functional status and reductions in health care service use, especially hospitals and nursing homes, for the frail elderly. The specific aims of this study are: 1) To systematically describe the patient population served by CARE in terms of their sociodemographic characteristics, health and functional status, and prior use of health services. A full descriptive analysis of the admissions to the day hospital will be conducted, and a detailed profile of participants who complete their programs of care will be established. 2) To identify and select an appropriate control group of sufficient size from Medicare administrative databases in order to be able to test the effectiveness of CARE. The control group will be selected from a new Medicare administrative database--the Medicare Current Beneficiary Survey--using a propensity scoring methodology and case-matching protocol based on the profile of CARE participants. 3) To assess the impact of CARE on emergency room use, hospitalizations, nursing home use, and functional status. Day hospital participants will be compared to the control group on these key outcome measures at selected time intervals. 4) To assess the strengths, weaknesses, and overall utility of using large administrative databases and innovative control group design methodology in quasi-experimental studies of patient outcomes and care effectiveness. A qualitative review of the overall methodology applied in the study will be undertaken, and the feasibility of deriving and using a control group from such databases in a nursing outcome study will be investigated.